CA1228031A - Disc-record player comprising a pressure member for pressing a record disc against the turntable - Google Patents
Disc-record player comprising a pressure member for pressing a record disc against the turntableInfo
- Publication number
- CA1228031A CA1228031A CA000479472A CA479472A CA1228031A CA 1228031 A CA1228031 A CA 1228031A CA 000479472 A CA000479472 A CA 000479472A CA 479472 A CA479472 A CA 479472A CA 1228031 A CA1228031 A CA 1228031A
- Authority
- CA
- Canada
- Prior art keywords
- turntable
- disc
- spring
- mandrel
- turns
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- 238000007906 compression Methods 0.000 claims abstract 2
- 230000002093 peripheral effect Effects 0.000 claims description 15
- 239000013598 vector Substances 0.000 description 8
- 238000004804 winding Methods 0.000 description 2
- 101100379067 Caenorhabditis elegans anc-1 gene Proteins 0.000 description 1
- 206010052804 Drug tolerance Diseases 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B17/00—Guiding record carriers not specifically of filamentary or web form, or of supports therefor
- G11B17/02—Details
- G11B17/022—Positioning or locking of single discs
- G11B17/028—Positioning or locking of single discs of discs rotating during transducing operation
- G11B17/0282—Positioning or locking of single discs of discs rotating during transducing operation by means provided on the turntable
Landscapes
- Holding Or Fastening Of Disk On Rotational Shaft (AREA)
Abstract
ABSTRACT:
A disc-record player comprises a pressure member for pressing a record disc against a turntable which car-ries a mandril at the upper side, the mandril being co-axial with the turntable and being engageable with the centre hole of the record disc. The pressure member com-prises spring means formed by turns of a toroidal coil compression spring which is accommodated in an annular space in the mandril, which space is open at the circum-ference of the mandril. The turns are clear of the mandril at the side facing the turntable axis. The spring turns are movable under spring force in radially inward outward directions relative to the turntable axis; they project from the circumference of the mandril and press the disc against the turntable.
A disc-record player comprises a pressure member for pressing a record disc against a turntable which car-ries a mandril at the upper side, the mandril being co-axial with the turntable and being engageable with the centre hole of the record disc. The pressure member com-prises spring means formed by turns of a toroidal coil compression spring which is accommodated in an annular space in the mandril, which space is open at the circum-ference of the mandril. The turns are clear of the mandril at the side facing the turntable axis. The spring turns are movable under spring force in radially inward outward directions relative to the turntable axis; they project from the circumference of the mandril and press the disc against the turntable.
Description
"Disc-record player cc~prising a pressure member for pressirlg a record disc against the turntable."
The invention relates to a disc-record player eomprising a turn-table and a pressure member for pressing a reeord dise against the turn-table, the turntable carryins on its upper side a mandril ~hich is eoaxial with the turntable and is engageable with the eentre hole of the dise, and the pressure member comprising sprina means whieh are accom-modated in the mandril and project frc~m the cireumference thereof, which are movable under spring force in radially inward and outwarc1 direetions relative to the turntable axis and which keep the ~isc presse~
against the turntahle.
A dise-reeord player of this type i.s disclosed in French Patent Speeifieation 2,078,456. In sueh a dise-reeord player the pressure nem.~er in aeecm~odatec1 in the mandri] whieh is situated above the turntable, so that for urqina the dise aaainst the turntable it is not neeessc~y to move a separate disc-pressure means dc~nwardly frcm a position a~ove the turntable and the height of the dise-reeord player above the turntable ean be limi.ted. In the knc~n disc-reeord player the spring means cor~fri.se three elastically supported balls arranged at the cireumference of the mandril. As a result of this, the reeord dise is urged against the turn-table at a few po.ints only. ~oreover, the three balls may not a1ways 20 exert equal pressures on the clisc. As a resu].t of this, the preC.snre exerted on the disc by the pressure n~her of the kno~.~n di.sc-record player ma~ be clistrihlted irregularly, so that in operation the disc is not situated in the eorreet position re].ative to the turntable and~or slip oeeurs between the disc and the turntab].e.
The invention aims at providina a dise-reeord pl.ayer of the t~.
defined in the openinq paragraph with a pressure r~ber ~aich acts against the record clisc at a l.arqe nun~r of points, the pressure .be.in~
distrih~ted Imifor~ly c~mong these points.
Accord:Lng to the invention the spring rneans compri.se t~lrns of a 30 eoil cc~pressicn spring ~1ich is accc~n~dated in an annular s~ce i.n the r~ldril, which space is open at the cireumferer1ce cf ,he m~ndril, ~hlch tun~s have a s~etrical shape relative to a plane which extends in a 3~
radial direction relative to the turntable axis and are clear of the mandril at the sides facing the turntable axis. This results in a pressure member which is capable of effective exerting a uniformly distributed pressure or! the disc at a large number of pressure points defined by the turns of the spring in order to ensure that the disc is positioned, correctly on the turntable in operation. Loading a record disc onto the turntable is nc~t impeded by this pressure n~mber because the turns of the coil campression spring can be urged radially inwards tc~ards the axis of the turntable~ Because of the small height above the turntable the pressure me~*~r is suitable for use in disc-record players in which a disc is brought into a position above the turntable upon insertion and is subsec~lently Ic~erecl onto t-lle turntable. An example of this is a disc-record player which is intended for playing optically readable audio discs of the "compact disc" type and which is installed behind the dash-board of a car.
It is to be noted that United States Patent Specificat:ion3,817,469 describes a pressure member having a toroidal coil spring whose turns draw the hub of a tape reel against a reel disc of a winding men~er.
As the spring is a tension spring whose turns are inclined at argles of approximately 40 relative to a plane which extends in a radial direction relative to the axis of rotation, the turns being drawn against the man-dril of the winding n~mber, the turns can be pressed radially inwards over a small distance or,ly and subsequently spring back when the reel hub is slid onto the spring. As a result of this the reel hub is not firmly kept in position. Therefore, the reel hub is clamped in position by means of a separate clamping device.
A preferred embodiment of the invention is characterized in that the mandril ccnnprises a cap which is situated above and spaced from the turntable and at its lower side is connected to a cylindrical sleeve 30 which extends from the cap up to the turntable, the annular space being bounded by surfaces of the cap, the sleeve and the turntable. This provides an easy-to-assemble turntable-and-mandril corn~ination in which the coil spring can be mo~nted in an effective manner. Inside the annular space the turns can mc~e effectively in a radially inward direction 35 when the disc is nK~ed over the n~ndril and then back in an outward direction after the disc has passed bel~ the n~axLmum diameter of the spring.
In connection with the foregoing another preferred embcdiment of t~le nverltiorl is character~zed in that ~e cap comprises a substantially 3~
PHN 11021 3 18-03-19(~5 frusto-cOnical peripheral portion which retains the turrs of the coil spring in said annular space at the side facing the turntable. The su~-stantially fr~sto-conical peripheral portior1 of the cap car perform a pre-centrincr function when the record d:isc is placed on the mandril as well as ensuring that the spring turrls cannot move out of the anr.ul r space in a radial direction.
A further preferred embcdiment of the invention is characterize1 in that inside the turns of -the coil spring there is arrangec'. a split ring, the ends of which clre separated by a gap. The split ring inside the tlnrnC
~0 of the coil spring limits the maximlm diameter of the coil sprina in the annular space. The use of the split ring not only ensures that the coil spring is retainecl effectively in the annular space but it also provides considerable freedcm in the design of the cross-sectional profile of the peripheral portion of the cap and the possibility for the sprincl t.~ns to be moved relatively far in a radially o~ltwar~ direction. This freedc~
in the choice of the profi]e of the peripheral portion of the cap an~1 the freedom of movement of the spring turns ensure that the spring turns act against the inner side of the periphera] portion at an opti~lm loca-tion for record discs of varying thickness and thu~s always exert a s~lb-20 stantially constant pressure on the record disc. The gap between the enc1sof the ring enables the turns of the coil spring to be slid onto the ring. Preferably, the ring is made of a sufficiently strong material to prevent it from being forced further open by the coil spring.
~o embodiments of the invention will nc~ be descr~bed in more 25 detail, by way of example, with ref~rence to the drawinqs. In the drawings:
Fig. 1 is an exploded perspective view of the turntclble, the press;~-e member and the mandril of one e~odiment of the invention;
Fiq. 2 is an axial sectional view, drawn to an enlarged scale, of 30 the turntahle, pressure m~ber and mar.dril shc~n in Fig. 1, sho~Jing a record disc pressed against the turntable ~y the pressure men~her;
Fig. 3 is an axial sectional view, drawn to an even larer scale, of a part of a second embcdiment of the invention, showing the pressure mP~*er in t~ positions corresponding to discs oF a minimum an(l n~XimLlm 35 thickness, respectively.
The drawings sh~ a turntable 1 which is rotatable ab~ut cm à~is la.
The turntable axis 1a forms the aYis of rotation of a hub 2 which is 2C~AT~33`~
P~l 11021 4 18-03-1985 integral with the turntable 1 and which is clamped on a spinclle 3.
At its circumference the turntable 1 has a raised rim 4 for supporting a record ~sc 5 which rim may be coat Y1 with a high-frictio? materi~l.
The disc 5, which in tl~e present eYamp e is of the compact~lisc type 5 and carries optically readable audio :Lnformation, has a centre ho]e wL1ose boundary wall 5a fits arour.d a raisecl central portion 6 of the turntahle which central por-tion is provided with a raisecl rim 6a for this purpose.
The lower end of a cylinc'rical sleeve 7 bears on the u~per surface 6b of the central portion 6 which sleeve is slicl onto the hub 2 ancl is fiYed relative to the hub in a manner not shown to rotate with i-t. Th sleeve 7 eYtends from the central portion 6 up to a cap 8 which is inte-gral with -the sleeve 7. The cap 8 comprises a flat disc-shaped ~in portion 9 ancl a f~J5tO-conical peripheral portion 10 whose dic~r~ter increases in the direction towards the turntable 1. The cap 8 and the raised rim 6a together constitute a mandril onto which the (1isc 5 c.~n ~
slid. ~.en the disc 5 is being placecl on the turntable, the outer surface 10b of the frusto-conical- peripheral portion 10 of the ca? 8 has a centring aetion which enables the clise to be pre-centred correctly on the turntable 1 by means of the boundary wall 5a of the hole in tne disc.
The outer surface 7a of the sleeve 7, the inner surface of the rim 6a and the llpper surface 6b of the eentral porticn 6 of the t~rntable an~l the lc~7er s~]rfaee 9a and inner surfaee 1na of the ~in and peripheral portions 9 and 10 respectively of the eap 8 bi~nd ar- annul~r space 11 in the mandril which accc~nmodates a toroidal eoil spring 12. .--ch sprina 25 turn 12a is syrmetrical relative to a plane which e~ctenc1s in a rad1a' direetion relative to the turntable aYis 1a. As a reslllt of t-his sha~e and the relatively large nur~er of turns, each turn 12a extends su'~
stantially perpendicularly to the surface 6b. Since the ~princ3 is a compreCision sprinc3, each turn 12a is pressff1 a~ainst the ri~ ~a and ~h 30 wall 10a, the turn ~eing spaced from the outtr surface 7a. The r~l ~a has a frusto conical inner surface ~.ose dia~leter increases 1n tht-~c~
tion away from the turntable, and the resultira co?verc~ei~ct of th1s ~r~r-face an1 the ~ner surface 10a of the peripheral ~ rtlon 10 of the cap c~
in -the radicllLy outwlrd direction serveci to erlsllre that the turns 1'l o.
35 the s??rincJ c mnot sprina Olt of the spc-lce 11, ~ ich i~s open at the Cil--cumfel-ence of tile r~-Lnc~il.
In ~n alt~rnatlve er~x~dirr~nt a split rirlc3 13 is ar2-~q~ rsile ti~
tu2-rl~ c-, of t~ - ?C3 1~ (51'? Fic~lre 3), L~ f ~he r!~c?
in Figure 1, being separatecl by a gap 14. The presence of the gap 14 enables the turns 12a to be slid onto the ring 13, which facilitates the mcunting of the spring on the ring, When the spring has been rr,ounted the gap 14 is bridged by a number of the turns 12a so that the turns of the spring are equi-spaced arolmd the circumference of the hub 2.
After a disc has been pre-centred on the outer surface 1Ob, the disc is slid do~n over the outer circumference of the spring 12.
As a result of the spacing relative to the outer wall 7a the t,urns 12a of the spring are pressed inwards towards the turntable axis 1a by t,he disc against their resilience ~mti] the disc has passed b~ the central plane of 'he spring, ~hich is the plane contaming the centres of -the turns 12a and where the sprinc~ has its maxin~m diameter. The turns th~n resile in the outward direction and exert a force on the bowndary ~ll 5a of the centre hole of the disc 5 to press the disc against the rim 4 l~ of the turntable. During rotation of the turntable the disc rotates with the turntable owing to the friction between the disc and the supportinc rim 4.
In ~ractice, the thickness of record discs of the above-mentionecl compact-disc type is subject to certain tolerances. Despite these tole-rances the pressure exerted on the disc by the turns 12a of the sprinq12 should remain substantially constant for various disc thicknesses.
For this purpose it is irnportant that the inner surface 1Oa of the peripheral portion 10 of the cap 8 does not significantly obstruct the radially outward movement of the hlrns of the spring. In a rnarner as shown in Fig. 3 for the second e~odiment, the spring 12 can still exert the desired pressure in the case of a record disc of rninir~hm thic',~-ness as a result of the outward vement of the spring turns 12a. In this respect the substar.tially upright position of each turn 12a is in~ortant.
In Fig. 3 this situation is represented by the unintern1pte,d lines. The ce~tre of a spring turn 12a is situated at the point bearing the referer1-ce numeral 15. The spring force of this turn 12a is represented by the force vector 16, ~1ich vector is unambiguously definecl both in resE~ect of its direction (radially of the axis 1a and ~erpendicular thereto) and in respect of it~s rnagnituAe (in conformity with the sprirg characte-ristics of the spring 12)~ The direction of the reactive force of theturn 12a on the peripheral portion 10 of the cap 8 is deterrQin~,~ by the line bet~er1 the centre 15 of the turn ar.d the point 17 at whlch -the turn touches the portion 10. Similarly, the directicn of the force exertecl by the t~rn 12a on the ~omdary wall 5a of the centre ho]e of the record disc 5 is determi,~ed hy the line between the point 15 and the point 18 at which Wle turn touches the wa~l 5a. The force d-agrc~l in I;i( .
5 3 shows how these lines yield the force veetors 19 and 20. The terrlimls of the vector 20 determines the vector 21 which extends paralle] to 'he axis 1a and which represents the clx ld L pressure exerted or- the rec or~
disc by the turn 12a.
The hroken lines in Fia. 3 represent the situation in the case of a 10 record disc of rnaximum thickness. In this situation it is not Imlikely that the magnitude of the pressure (vector 21! deviates strongly due to the inward move~rent of the spring turns 12a. This can be precluded by .a correct choice of the cross-sectional profile of the peripheral portion 10 of the eap 8, in particular the profile of the inner s~1rfaee 10a of the 15 portion 10. As a result of the larger thickr.ess of the recorcl dise the centre 15a of a spring turn is situated more inwardly anc1 slightly higher re~ative to the turntable 1 than the centre 15 of the spring turn in the case of a disc of minimum thickness. The force veetor 16a is un-ambiguously defined in the same way as the vector 16. There is a difI'erer-20 ce in the point 17a at which the spring turn 12a touches the irmer sur-faee 10a of the peripheral portion 10 of the eap 8; the ]oeation of this point 17a relative to the axis 1a depends on the profile of the surface 10. A suitable loeation of the point 17a is obtained by givinq the sur-face 10a a coneave shape such that the point 17a is displac~-~1 as fr~r as 25 possible in a radially inward direetion. In this way the point 1~a a~
which the sprinc3 turn 12a touehes the wall 5a of the centre noLe o'~ thc reeord dise, the vectors 19a and 20a prc,vide the pressllre as represe;nt~:
by the vector 21a. Thus, the pressure exerted on a record dlsc can `æ
rnaintained eonstant within reasonal le limits both in the ease of a disc 30 of minimum thickness an-1 in the ease of a disc of rnc~xir~m thic!;ness.
The force diaa,rc~ls shown in Fig. 3 illustrate that the press~lre d~s not vc~y ~y n~re than approxirnately 20~ with recorc1 d ses of min~ m ~-.n~' rnaxim~lm thic);ness. This ensures a satisfactol-y o~er~tlon o' the presC;~re n~mber for va}-yinc3 thiekr,esses of the discs.
The pressul e ~ 3nl~?r eormprislng the coil sprir.c~ 12 ensures tha~ ~ e reCOr(`! dlSC iS pre;s~c-~-l onto the s~lprcx~rtmq rim ~ of the turr~ l? ln unlfonn manner at a very larc-Je nun~er of press~lre ,~in~s de~lne~ t F~ 11021 7 18-03-1985 turns 12a of the spring. This has the advantage that with a minimum number of parts the height or the pressure member above the turntable 1 ean be minimized. As a resul.t of this, this eonstruetion is particularly suitable for disc-record players which are accomm~dated in a co~pact housing, such as a disc-record pla~er intended for use in a motor car.
The invention relates to a disc-record player eomprising a turn-table and a pressure member for pressing a reeord dise against the turn-table, the turntable carryins on its upper side a mandril ~hich is eoaxial with the turntable and is engageable with the eentre hole of the dise, and the pressure member comprising sprina means whieh are accom-modated in the mandril and project frc~m the cireumference thereof, which are movable under spring force in radially inward and outwarc1 direetions relative to the turntable axis and which keep the ~isc presse~
against the turntahle.
A dise-reeord player of this type i.s disclosed in French Patent Speeifieation 2,078,456. In sueh a dise-reeord player the pressure nem.~er in aeecm~odatec1 in the mandri] whieh is situated above the turntable, so that for urqina the dise aaainst the turntable it is not neeessc~y to move a separate disc-pressure means dc~nwardly frcm a position a~ove the turntable and the height of the dise-reeord player above the turntable ean be limi.ted. In the knc~n disc-reeord player the spring means cor~fri.se three elastically supported balls arranged at the cireumference of the mandril. As a result of this, the reeord dise is urged against the turn-table at a few po.ints only. ~oreover, the three balls may not a1ways 20 exert equal pressures on the clisc. As a resu].t of this, the preC.snre exerted on the disc by the pressure n~her of the kno~.~n di.sc-record player ma~ be clistrihlted irregularly, so that in operation the disc is not situated in the eorreet position re].ative to the turntable and~or slip oeeurs between the disc and the turntab].e.
The invention aims at providina a dise-reeord pl.ayer of the t~.
defined in the openinq paragraph with a pressure r~ber ~aich acts against the record clisc at a l.arqe nun~r of points, the pressure .be.in~
distrih~ted Imifor~ly c~mong these points.
Accord:Lng to the invention the spring rneans compri.se t~lrns of a 30 eoil cc~pressicn spring ~1ich is accc~n~dated in an annular s~ce i.n the r~ldril, which space is open at the cireumferer1ce cf ,he m~ndril, ~hlch tun~s have a s~etrical shape relative to a plane which extends in a 3~
radial direction relative to the turntable axis and are clear of the mandril at the sides facing the turntable axis. This results in a pressure member which is capable of effective exerting a uniformly distributed pressure or! the disc at a large number of pressure points defined by the turns of the spring in order to ensure that the disc is positioned, correctly on the turntable in operation. Loading a record disc onto the turntable is nc~t impeded by this pressure n~mber because the turns of the coil campression spring can be urged radially inwards tc~ards the axis of the turntable~ Because of the small height above the turntable the pressure me~*~r is suitable for use in disc-record players in which a disc is brought into a position above the turntable upon insertion and is subsec~lently Ic~erecl onto t-lle turntable. An example of this is a disc-record player which is intended for playing optically readable audio discs of the "compact disc" type and which is installed behind the dash-board of a car.
It is to be noted that United States Patent Specificat:ion3,817,469 describes a pressure member having a toroidal coil spring whose turns draw the hub of a tape reel against a reel disc of a winding men~er.
As the spring is a tension spring whose turns are inclined at argles of approximately 40 relative to a plane which extends in a radial direction relative to the axis of rotation, the turns being drawn against the man-dril of the winding n~mber, the turns can be pressed radially inwards over a small distance or,ly and subsequently spring back when the reel hub is slid onto the spring. As a result of this the reel hub is not firmly kept in position. Therefore, the reel hub is clamped in position by means of a separate clamping device.
A preferred embodiment of the invention is characterized in that the mandril ccnnprises a cap which is situated above and spaced from the turntable and at its lower side is connected to a cylindrical sleeve 30 which extends from the cap up to the turntable, the annular space being bounded by surfaces of the cap, the sleeve and the turntable. This provides an easy-to-assemble turntable-and-mandril corn~ination in which the coil spring can be mo~nted in an effective manner. Inside the annular space the turns can mc~e effectively in a radially inward direction 35 when the disc is nK~ed over the n~ndril and then back in an outward direction after the disc has passed bel~ the n~axLmum diameter of the spring.
In connection with the foregoing another preferred embcdiment of t~le nverltiorl is character~zed in that ~e cap comprises a substantially 3~
PHN 11021 3 18-03-19(~5 frusto-cOnical peripheral portion which retains the turrs of the coil spring in said annular space at the side facing the turntable. The su~-stantially fr~sto-conical peripheral portior1 of the cap car perform a pre-centrincr function when the record d:isc is placed on the mandril as well as ensuring that the spring turrls cannot move out of the anr.ul r space in a radial direction.
A further preferred embcdiment of the invention is characterize1 in that inside the turns of -the coil spring there is arrangec'. a split ring, the ends of which clre separated by a gap. The split ring inside the tlnrnC
~0 of the coil spring limits the maximlm diameter of the coil sprina in the annular space. The use of the split ring not only ensures that the coil spring is retainecl effectively in the annular space but it also provides considerable freedcm in the design of the cross-sectional profile of the peripheral portion of the cap and the possibility for the sprincl t.~ns to be moved relatively far in a radially o~ltwar~ direction. This freedc~
in the choice of the profi]e of the peripheral portion of the cap an~1 the freedom of movement of the spring turns ensure that the spring turns act against the inner side of the periphera] portion at an opti~lm loca-tion for record discs of varying thickness and thu~s always exert a s~lb-20 stantially constant pressure on the record disc. The gap between the enc1sof the ring enables the turns of the coil spring to be slid onto the ring. Preferably, the ring is made of a sufficiently strong material to prevent it from being forced further open by the coil spring.
~o embodiments of the invention will nc~ be descr~bed in more 25 detail, by way of example, with ref~rence to the drawinqs. In the drawings:
Fig. 1 is an exploded perspective view of the turntclble, the press;~-e member and the mandril of one e~odiment of the invention;
Fiq. 2 is an axial sectional view, drawn to an enlarged scale, of 30 the turntahle, pressure m~ber and mar.dril shc~n in Fig. 1, sho~Jing a record disc pressed against the turntable ~y the pressure men~her;
Fig. 3 is an axial sectional view, drawn to an even larer scale, of a part of a second embcdiment of the invention, showing the pressure mP~*er in t~ positions corresponding to discs oF a minimum an(l n~XimLlm 35 thickness, respectively.
The drawings sh~ a turntable 1 which is rotatable ab~ut cm à~is la.
The turntable axis 1a forms the aYis of rotation of a hub 2 which is 2C~AT~33`~
P~l 11021 4 18-03-1985 integral with the turntable 1 and which is clamped on a spinclle 3.
At its circumference the turntable 1 has a raised rim 4 for supporting a record ~sc 5 which rim may be coat Y1 with a high-frictio? materi~l.
The disc 5, which in tl~e present eYamp e is of the compact~lisc type 5 and carries optically readable audio :Lnformation, has a centre ho]e wL1ose boundary wall 5a fits arour.d a raisecl central portion 6 of the turntahle which central por-tion is provided with a raisecl rim 6a for this purpose.
The lower end of a cylinc'rical sleeve 7 bears on the u~per surface 6b of the central portion 6 which sleeve is slicl onto the hub 2 ancl is fiYed relative to the hub in a manner not shown to rotate with i-t. Th sleeve 7 eYtends from the central portion 6 up to a cap 8 which is inte-gral with -the sleeve 7. The cap 8 comprises a flat disc-shaped ~in portion 9 ancl a f~J5tO-conical peripheral portion 10 whose dic~r~ter increases in the direction towards the turntable 1. The cap 8 and the raised rim 6a together constitute a mandril onto which the (1isc 5 c.~n ~
slid. ~.en the disc 5 is being placecl on the turntable, the outer surface 10b of the frusto-conical- peripheral portion 10 of the ca? 8 has a centring aetion which enables the clise to be pre-centred correctly on the turntable 1 by means of the boundary wall 5a of the hole in tne disc.
The outer surface 7a of the sleeve 7, the inner surface of the rim 6a and the llpper surface 6b of the eentral porticn 6 of the t~rntable an~l the lc~7er s~]rfaee 9a and inner surfaee 1na of the ~in and peripheral portions 9 and 10 respectively of the eap 8 bi~nd ar- annul~r space 11 in the mandril which accc~nmodates a toroidal eoil spring 12. .--ch sprina 25 turn 12a is syrmetrical relative to a plane which e~ctenc1s in a rad1a' direetion relative to the turntable aYis 1a. As a reslllt of t-his sha~e and the relatively large nur~er of turns, each turn 12a extends su'~
stantially perpendicularly to the surface 6b. Since the ~princ3 is a compreCision sprinc3, each turn 12a is pressff1 a~ainst the ri~ ~a and ~h 30 wall 10a, the turn ~eing spaced from the outtr surface 7a. The r~l ~a has a frusto conical inner surface ~.ose dia~leter increases 1n tht-~c~
tion away from the turntable, and the resultira co?verc~ei~ct of th1s ~r~r-face an1 the ~ner surface 10a of the peripheral ~ rtlon 10 of the cap c~
in -the radicllLy outwlrd direction serveci to erlsllre that the turns 1'l o.
35 the s??rincJ c mnot sprina Olt of the spc-lce 11, ~ ich i~s open at the Cil--cumfel-ence of tile r~-Lnc~il.
In ~n alt~rnatlve er~x~dirr~nt a split rirlc3 13 is ar2-~q~ rsile ti~
tu2-rl~ c-, of t~ - ?C3 1~ (51'? Fic~lre 3), L~ f ~he r!~c?
in Figure 1, being separatecl by a gap 14. The presence of the gap 14 enables the turns 12a to be slid onto the ring 13, which facilitates the mcunting of the spring on the ring, When the spring has been rr,ounted the gap 14 is bridged by a number of the turns 12a so that the turns of the spring are equi-spaced arolmd the circumference of the hub 2.
After a disc has been pre-centred on the outer surface 1Ob, the disc is slid do~n over the outer circumference of the spring 12.
As a result of the spacing relative to the outer wall 7a the t,urns 12a of the spring are pressed inwards towards the turntable axis 1a by t,he disc against their resilience ~mti] the disc has passed b~ the central plane of 'he spring, ~hich is the plane contaming the centres of -the turns 12a and where the sprinc~ has its maxin~m diameter. The turns th~n resile in the outward direction and exert a force on the bowndary ~ll 5a of the centre hole of the disc 5 to press the disc against the rim 4 l~ of the turntable. During rotation of the turntable the disc rotates with the turntable owing to the friction between the disc and the supportinc rim 4.
In ~ractice, the thickness of record discs of the above-mentionecl compact-disc type is subject to certain tolerances. Despite these tole-rances the pressure exerted on the disc by the turns 12a of the sprinq12 should remain substantially constant for various disc thicknesses.
For this purpose it is irnportant that the inner surface 1Oa of the peripheral portion 10 of the cap 8 does not significantly obstruct the radially outward movement of the hlrns of the spring. In a rnarner as shown in Fig. 3 for the second e~odiment, the spring 12 can still exert the desired pressure in the case of a record disc of rninir~hm thic',~-ness as a result of the outward vement of the spring turns 12a. In this respect the substar.tially upright position of each turn 12a is in~ortant.
In Fig. 3 this situation is represented by the unintern1pte,d lines. The ce~tre of a spring turn 12a is situated at the point bearing the referer1-ce numeral 15. The spring force of this turn 12a is represented by the force vector 16, ~1ich vector is unambiguously definecl both in resE~ect of its direction (radially of the axis 1a and ~erpendicular thereto) and in respect of it~s rnagnituAe (in conformity with the sprirg characte-ristics of the spring 12)~ The direction of the reactive force of theturn 12a on the peripheral portion 10 of the cap 8 is deterrQin~,~ by the line bet~er1 the centre 15 of the turn ar.d the point 17 at whlch -the turn touches the portion 10. Similarly, the directicn of the force exertecl by the t~rn 12a on the ~omdary wall 5a of the centre ho]e of the record disc 5 is determi,~ed hy the line between the point 15 and the point 18 at which Wle turn touches the wa~l 5a. The force d-agrc~l in I;i( .
5 3 shows how these lines yield the force veetors 19 and 20. The terrlimls of the vector 20 determines the vector 21 which extends paralle] to 'he axis 1a and which represents the clx ld L pressure exerted or- the rec or~
disc by the turn 12a.
The hroken lines in Fia. 3 represent the situation in the case of a 10 record disc of rnaximum thickness. In this situation it is not Imlikely that the magnitude of the pressure (vector 21! deviates strongly due to the inward move~rent of the spring turns 12a. This can be precluded by .a correct choice of the cross-sectional profile of the peripheral portion 10 of the eap 8, in particular the profile of the inner s~1rfaee 10a of the 15 portion 10. As a result of the larger thickr.ess of the recorcl dise the centre 15a of a spring turn is situated more inwardly anc1 slightly higher re~ative to the turntable 1 than the centre 15 of the spring turn in the case of a disc of minimum thickness. The force veetor 16a is un-ambiguously defined in the same way as the vector 16. There is a difI'erer-20 ce in the point 17a at which the spring turn 12a touches the irmer sur-faee 10a of the peripheral portion 10 of the eap 8; the ]oeation of this point 17a relative to the axis 1a depends on the profile of the surface 10. A suitable loeation of the point 17a is obtained by givinq the sur-face 10a a coneave shape such that the point 17a is displac~-~1 as fr~r as 25 possible in a radially inward direetion. In this way the point 1~a a~
which the sprinc3 turn 12a touehes the wall 5a of the centre noLe o'~ thc reeord dise, the vectors 19a and 20a prc,vide the pressllre as represe;nt~:
by the vector 21a. Thus, the pressure exerted on a record dlsc can `æ
rnaintained eonstant within reasonal le limits both in the ease of a disc 30 of minimum thickness an-1 in the ease of a disc of rnc~xir~m thic!;ness.
The force diaa,rc~ls shown in Fig. 3 illustrate that the press~lre d~s not vc~y ~y n~re than approxirnately 20~ with recorc1 d ses of min~ m ~-.n~' rnaxim~lm thic);ness. This ensures a satisfactol-y o~er~tlon o' the presC;~re n~mber for va}-yinc3 thiekr,esses of the discs.
The pressul e ~ 3nl~?r eormprislng the coil sprir.c~ 12 ensures tha~ ~ e reCOr(`! dlSC iS pre;s~c-~-l onto the s~lprcx~rtmq rim ~ of the turr~ l? ln unlfonn manner at a very larc-Je nun~er of press~lre ,~in~s de~lne~ t F~ 11021 7 18-03-1985 turns 12a of the spring. This has the advantage that with a minimum number of parts the height or the pressure member above the turntable 1 ean be minimized. As a resul.t of this, this eonstruetion is particularly suitable for disc-record players which are accomm~dated in a co~pact housing, such as a disc-record pla~er intended for use in a motor car.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A disc player comprising a turntable for receiving a disc thereagainst, said turntable having an axis of rotation;
a generally cylindrical mandrel projecting above said turntable coaxially with said axis, said mandrel being sized substantially as a central hole in said disc, said mandrel having therein an annular space which is open at the circumference of the mandrel;
a toroidal coil spring in said annular space, said spring being loaded in compression and having turns which are each substantially coplanar with said turntable axis, the outer circumference of said spring extending beyond the circumference of said mandrel where said annular space is open, the inner circumference of said spring being clear of the mandrel, said spring having a central plane parallel to said turntable and spaced therefrom by a dis-tance sufficient to ensure pressing said disc against said turntable, said distance being greater than the maximum expected disc thickness.
a generally cylindrical mandrel projecting above said turntable coaxially with said axis, said mandrel being sized substantially as a central hole in said disc, said mandrel having therein an annular space which is open at the circumference of the mandrel;
a toroidal coil spring in said annular space, said spring being loaded in compression and having turns which are each substantially coplanar with said turntable axis, the outer circumference of said spring extending beyond the circumference of said mandrel where said annular space is open, the inner circumference of said spring being clear of the mandrel, said spring having a central plane parallel to said turntable and spaced therefrom by a dis-tance sufficient to ensure pressing said disc against said turntable, said distance being greater than the maximum expected disc thickness.
2. The disc player of Claim 1 wherein said spring is captured by said mandrel to maintain compressive loading.
3. The disc player of Claim 1 wherein inside the turns of said coil there is a split ring.
4. The disc player of Claim 1 wherein said annular space is sized to permit axial movement of said toroidal coil spring relative to the turntable when a disc is pressed thereagainst.
5. The disc player of Claim 4 wherein said annular space is bounded by a peripheral inner surface opposite said turntable and facing said axis, said inner surface converging from where said annular space is open toward said axis.
6. The disc player of Claim 5 wherein said peri-pheral inner surface is a frusto-conical surface.
7. The disc player of Claim 5 wherein said peri-pheral inner surface is a concave surface.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8401304 | 1984-04-20 | ||
| NL8401304A NL8401304A (en) | 1984-04-20 | 1984-04-20 | RECORD PLAYER WITH A PRESSURE JOINT FOR PRESSING A PLATE LOCATED ON THE TURNTABLE. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1228031A true CA1228031A (en) | 1987-10-13 |
Family
ID=19843843
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000479472A Expired CA1228031A (en) | 1984-04-20 | 1985-04-18 | Disc-record player comprising a pressure member for pressing a record disc against the turntable |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4649532A (en) |
| EP (1) | EP0159100B1 (en) |
| JP (1) | JPS60234259A (en) |
| CA (1) | CA1228031A (en) |
| DE (1) | DE3566933D1 (en) |
| NL (1) | NL8401304A (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4958839A (en) * | 1988-07-12 | 1990-09-25 | Guzik Technical Enterprises, Inc. | Disc clamp employing resilient cone for spreading balls |
| JP2799189B2 (en) * | 1989-07-11 | 1998-09-17 | 株式会社ケンウッド | Disc player disc holding mechanism |
| JP2861144B2 (en) * | 1989-11-16 | 1999-02-24 | ソニー株式会社 | Disc chucking mechanism |
| US5270999A (en) * | 1990-12-10 | 1993-12-14 | Conner Peripherals, Inc. | Apparatus and method for reducing disk distortion |
| JP3384002B2 (en) * | 1992-01-24 | 2003-03-10 | ソニー株式会社 | Disc table and recording and / or reproducing apparatus |
| AT397737B (en) * | 1992-06-10 | 1994-06-27 | Koninkl Philips Electronics Nv | DEVICE FOR PLAYING A DISK-SHAPED RECORD CARRIER |
| JPH06131783A (en) * | 1992-10-19 | 1994-05-13 | Asahi Corp:Kk | Disk holder |
| JP2842521B2 (en) | 1994-12-28 | 1999-01-06 | 三菱電機株式会社 | Interchangeable storage device, recording medium cartridge, and method of using slot for card type device |
| DE19644158A1 (en) * | 1996-10-24 | 1998-04-30 | Grundig Ag | Method and device for gripping objects with a through opening |
| US6041033A (en) * | 1996-12-18 | 2000-03-21 | Matsushita Electric Industrial Co., Ltd. | Disk holding device |
| US5905923A (en) * | 1998-02-02 | 1999-05-18 | Sensormatic Electronics Corporation | Video camera mounting assembly with friction bearings for inhibiting pan and tilt movements |
| DE19859356A1 (en) * | 1998-12-22 | 2000-06-29 | Thomson Brandt Gmbh | Recording or playback device with a holder for disc-shaped recording media |
| US6697320B2 (en) * | 2001-06-13 | 2004-02-24 | Lite-On It Corporation | Clamping device with variable clamping force |
| EP1424693A1 (en) * | 2002-11-28 | 2004-06-02 | Sunonwealth Electric Machine Industry Co., Ltd. | Holding device for an optical disk drive |
| JP2004234773A (en) * | 2003-01-31 | 2004-08-19 | Tokyo Parts Ind Co Ltd | Turn table |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2833488A (en) * | 1956-05-24 | 1958-05-06 | John Dusenbery Company Inc | Expansible core adapter |
| US3083927A (en) * | 1960-05-13 | 1963-04-02 | Lockheed Aircraft Corp | Spindle |
| DE7005274U (en) * | 1970-02-14 | 1970-05-21 | Buehler Gmbh Nachf Geb | PLATTER IN RECORD PLAYERS FOR TOYS. |
| US3817469A (en) * | 1973-05-11 | 1974-06-18 | Bucode | Self-positioning reel latching hub |
| US4022478A (en) * | 1975-07-03 | 1977-05-10 | Zenith Radio Corporation | Push-button video disc hub |
| US4077236A (en) * | 1976-03-11 | 1978-03-07 | Shugart Associates | Apparatus having inwardly biased fingers hingedly attached to a hub for clamping and driving a flexible disc |
| JPS5642857Y2 (en) * | 1976-06-22 | 1981-10-07 | ||
| JPS5573968A (en) * | 1978-11-29 | 1980-06-04 | Watanabe Kenkyusho:Kk | Simple record player |
| JPS58194181A (en) * | 1982-05-01 | 1983-11-12 | Asahi Optical Co Ltd | Disc clamping device |
| NL8301681A (en) * | 1983-05-11 | 1984-12-03 | Philips Nv | RECORD PLAYER WITH A PRESSURE JOINT FOR PRESSING A PLATE LOCATED ON THE TURNTABLE. |
-
1984
- 1984-04-20 NL NL8401304A patent/NL8401304A/en not_active Application Discontinuation
-
1985
- 1985-04-04 US US06/719,949 patent/US4649532A/en not_active Expired - Fee Related
- 1985-04-16 DE DE8585200584T patent/DE3566933D1/en not_active Expired
- 1985-04-16 EP EP85200584A patent/EP0159100B1/en not_active Expired
- 1985-04-17 JP JP60080417A patent/JPS60234259A/en active Granted
- 1985-04-18 CA CA000479472A patent/CA1228031A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60234259A (en) | 1985-11-20 |
| US4649532A (en) | 1987-03-10 |
| NL8401304A (en) | 1985-11-18 |
| DE3566933D1 (en) | 1989-01-26 |
| JPH0477983B2 (en) | 1992-12-09 |
| EP0159100A1 (en) | 1985-10-23 |
| EP0159100B1 (en) | 1988-12-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |